Various terms are defined in the following specification. For convenience, a Glossary of terms is provided herein, immediately preceding the claims.
Tetrakis(perfluoroaryl)borate derivatives are useful as activators/co-catalysts for metallocenes in processes for polymerization of olefins to polymers. For example, such derivatives are useful in the polymerization of linear copolymers of ethylene. There are many publications related to the preparation of these activators/co-catalysts. See, for example, Li, L. and Marks, T. J., Organometallics 1998, 17, 3996-4003; U.S. Pat. No. 6,635,597; U.S. Pat. No. 5,679,289; and U.S. Pat. No. 6,580,007. In particular, Mars, et al., WO 99/06412, describes a modified procedure of Gething, et al., J. Chem. Soc. 1962, 36, 186, for making a precursor to the tetrakis(perfluoroaryl)borate, i.e., heptafluoro-2-naphthylhydrazine, from octafluoronaphthalene by reaction with hydrazine hydrate. The process uses stoichiometric quantities of hydrazine and octafluoronaphthlene (OFN) and reacts them together at reflux in ethanol. Various publications list the boiling point of ethanol as about 78° C. The reported procedures for making tetra(perfluoroaryl)borate salts and the related triarylboranes usually involve lithiating the fluorinated precursor in a hydrocarbon solvent, or the use of Grignard reagents in ether solution (see, e.g., U.S. Pat. No. 6,700,019). None of these reported procedures are suitable for making tetrarylborates in high enough yields and with purities that are suitable for commercial use. Furthermore, the lithiation of 2-bromoheptafluoronaphthalene, in pentane solvent, as reported in Li, L, and Marks, T, J. Organometallics 1998, 17, 3996-4003, caused the lithium derivative to precipitate. This could present difficulties in the event of the expected exothermic decomposition. Improved processes are thus needed.